Cylinder head for internal combustion engines



Dec. 13, 1938.' q A. SCHWARZ 2,139,978

CYLINDER HEAD FOR INTERNAL COMBUSTION ENGINES Original Fi led Dec. 2 1. 1934 2 Sheets-Sheet 1 INVENTOR ALFRED SCHWARZ FIG.6 WWLW' I ATTORNEYS 13, 1938. A. scHwARz CYLINDER HEAD FOR INTERNAL COMBUSTION ENGINES Original Filed Ded. 21. 1954 2 Sheets-Sheet 2 FIG.3

A INVENTOR ALFRED SCHWARZ Patented Dec. 13, 1938 CYLINDER HEAD FOR INTERNAL COMBUS- I'ION ENGINES Alfred Schwarz', Montclair, N. J., asaignor to The Economy Engineering Corporation, New York, N. Y., a corporation of Delaware Application 8 Claims.

This invention relates to improvements in cylinder heads for internal combustion engines, and is a continuation in part of -my co-pending application Ser. No. 680,635 filed July 14, 1933.

In my earlier application aforesaid, I have described the advantages of forming the combustion chamber of an internal combustion engine by 'means of a cylinder-head in which the metal distribution is pre-calculated so that the temperature of various portions of the combustion chamber will, after compression, be substantially uniform and avoid overheating a portion of the charge and thereby cause its too early decomposition and therefore prevent what has come to be known as detonation.

In the operation of an internal combustion en- December 21, 1934, Serial No. 758,598 Renewed March 12, 1938 gine it requires but a fraction of a second to perform 'the functions of compressing the charge and exploding the same in a cylinder and it is cylinder under the most favorable conditions at the time of its ignition and combustion.

Apparently the best conditions exist-when the charge is present in the cylinder in a highly compressed condition and properly'heated, by both compression and other means. i

It is well known that there is a critical temperature at which each fuel will automatically ignite and that the fuel-air mixture ,should be present in the cylinder in a highly compressed state,- and that the temperature thereof should be uniform throughout the compressed charge. Moreover, this-compression-end temperature, so to speak, should be close to but slightly below the critical temperature, known as the auto-ignition temperature. When the charge is properly pre-, pared, it may be electrically ignited and combustion will take place at a rate of flame propagation proportional to the temperature of the charge and bear a relation to theamount of its compres previous patent application, for forming a combustion chamber having a substantially uniform interior wall temperature, which wall temperature should bear a relation to the compression ratio.

In the past when water cooled cylinder heads were molded from cast iron or other metals, it was; necessary to make the thickness of the wall forming the combustion chamber sufflcient to permit the hot metal to flow through such molds and therefore the wall thickness was not limited by the temperature requirements of the combustion chamber but by the requirements of the method of manufacture. Furthermore, bosses had to be provided for the spark plug, the stud bolts, water connections, timer shafts, etc., and

when they were located near the combustion chamber the metal of the bosses wasnecessarily integral with that of the the walls of the combustion chamber and incidentally placed quantitles of 'metal near the combustion chamber walls which are capable of absorbing .heat, and which, during the operation of the engine, became, in eflfect, hot spots capable of pre-igniting the charge and causing detonation.

I have also found-that it is dimcult to cast cylinder heads having cored water jackets and,

-One reason for this difficulty in making cast' cylinder heads as heretofore, is that the cores for forming the water jacket often become shift.-

' ed or mutilated during the molding and casting sion atthe, time it was ignited. If interior portions of the cylinder head have different tem- 'peraturesdue to operating conditions,'a variable heat transfer would -take-place between the charge and it's confining walls and the hotter portions-of the charge would burn faster and the cooler portions burn slower. Such burning 11'? regularities manifest themselves in what is referred to above as detonation. Such detonation operation, and result in more or less indeter-' minat'e wall thicknesses, Accordingly, it is desirabie to. construct. a cylinder head so that the combustion chamber walls may be machined toif necessary, after the castchamber wall. I have discovered, howe ver,- by

the aid of thermo-couples applied during power tests, that temperature differences of from to 200 F. are oftenpresent within a, smallcomresults inan uneconomical operation of the' errgine..

An object of the invention, therefore,1s to proof various'po'rtions of the'h'ead equalized, an inbustion chamberfan'd that when-such parasite metal was properly removed, and the temperature respectively from hotter and colder portions of the charge.

If the entire charge is of a correct temperature, except for one small portion which is at a higher temperature, then this will prevent the use of a higher compression ratio, because the hot spot will then pre-ignite the charge.

An important object of my invention, therefore is'the production of an improved cylinder head comprising a chamber or water jacket. formed about a cast head plate by means of a pressed steel top -or cover for said plate having the edges thereof crimped beneath the'edge of the plate, or otherwise suitably secured thereto.

Another object of my present invention is the production of a combustion chamber, in which different portions of the walls thereof are of different and predetermined thicknesses, and to devise means to attach such combustion chamber to the cylinder block of the engine without having the heat transfer, or a heat retention, from the walls or construction members of the combustion chamber disturb the heat balance in said chamber.

Other objects and advantages of my invention will become apparent or be specifically referred to in the following description thereof taken in connection with the accompanying drawings, in

which;

Figure 1 illustrates across-sectional assembly viewof my improved heat balanced cylinder head mounted on the cylinder block on an internal combustion engine. The view of the head plate in this figure is taken on line l--i of "Figure 2.

head plate.

Figure 7 illustrates a modified form of my assembled water jacket in which the head plate is confined in a sheet metal casing, which casing comprises a fiat perforated plate and a water jacket welded together at the periphery thereof.

Referring now to the drawings, it will be seen thatFigure 1 illustrates a fragmentary crosssectional view of a common type of L-head ene gine equipped with my improved cylinder head. This engine comprises a cylinder I, a piston 2,

a space 3 about 'the cylinder, through which cooling water may be circulated, and a cylinder head (not numbered) comprising a head plate 5 and cover 6 forming a space 1 above the plate 5 through which cooling water is circulated through the assembled head. The cover 6 is made from a. sheet metal stamping having a skirt or side around the edge of the head plate 5 and the skirt is crimped about this head by means of forming dies l and H, see Figure 6. By constructing the head plate with a head of this type, the forming dies may be made with a clearance i2 at the bottom (top in Fig. 6) and may be otherwise adapted to exert their forming pressures on either side of the bead rather than subjecting the stud bosses l3 thereto. The head is secured to the cylinder block in the usual way by stay bolts I. It will be understood that a gasket 15 is interposed between the cylinder block and head, in the usual way and that sealing washers I 6 are disposed under the heads of each of the stay bolts l4. Finally the edge I! of the spark plug hole I8 is rolled into a recess provided in the head plate 5. When the head plate and cover 6 are assembled as described, no attempt is made to seal the cover to the head, because this is done solely by clamping the head plate to the cylinder block between the gasket l5 and washers, 6. It will be particularly noted that the turned under portion of the cover 6 fits in a recess I9, see Fig. 3, formed in the face of the head plate and that the edge ll" of the cover extends far enough into this recess and under the edge of the head plate 5 to be effectively sealed thereto when the assembly is clamped by the studs I4 to the block.

Figure 1 also illustrates an intake port I, and an intake valve V, which is operated during the engine cycle by any suitable means, as is the exhaust valve, not shown, although preferably located proximate thereto.

Figure 1 further illustrates a combustion chamber formed above the cylinder by the head plate '5. This chamber comprises a large volume pormay contain 15% or less. -If Figure 1 illustrated a cast iron cylinder head as ordinarily constructed, that is, with a combustion chamber wall of uniformcross-section throughout, it would be found that the lower surface of the head wall proximate the crescent-shaped space 22 would be one of the best cooled surfaces of the head, notwithstanding the amount of heat in the volume of the charge in contact therewith is relatively small when the piston is at upper dead center. Operating at a compression ratio of five to one with the jacket water at 150,F. the cooling surface adjacent the crescent 22 of the combustion chamber was about 300 F. The temperature variations in other portions of the combustion chamber were approximately as fol lows: namely, the exhaust valve was about 900 F.; the cylinder block surface adjacent the exhaust valve wasabout 700 F. the head wall over the exhaust valve was about 600 F.; the intake valve was about 250 F.; the surface of the head block adjacent the intake valve was about 275 F. and the surface over the intake somewhat higher.

Bearing in mind that the heating due to compression by the piston is precisely the same for all of the charge, and that in this case the normal near the intake and above the lines A"B, see

Figure 4, and in the crescent space 22 over the piston, will be much cooler than in the region below the line A B which is near the hot quently, this part of the charge is partly taken heretofore been comparatively cool.

my copending applicationSeri'al No. 680,365, and

care of because most of it is burned by the time its radiant heat and pressure have beenable to produce high pressures and temperatures in the remaining parts of the charge.

In the above case where the compression ratio was five to one, I found that under normal operating conditions the part of the charge in' the region below the line AB was raised from its normal compression temperature of 525 F. up to 600 F.,

that there was a general temperature difierential of 200-F. which favored secondary decomposition of the fuel and detonation. Of course the actual charge temperature cannot be determined as accurately as the wall temperatures and it is obvious that with the above general differential of approximately 200 F., for the two characteristically different regions of the charge, there are certain parts of the charge in each region in which the local charge temperatures are respectively higher and lower thflIlthOSB indicated above.

In Figure l -I have shown more orless diagrammatically how a practical approximation of uniformity of charge temperature may be obtained by a'very simple means. In this case the crescent-shaped wall at 23, see also Fig. 4, defining the thin compression space above the piston, has been made much thicker than heretofore to decrease the dissipation, by the cooling means, of the heat at this point, and enable the thickened walls to actually store up more heat than heretofore, and thereby elevate the temperatureof the charge in that part of the combustion chamber which has As stated'in above referred to, the 'thicknessof the wall por-' tion 23 overlying the engine cylinder region may be 58inch, the thickness of the Wall portion '24 overlying the exhaust valve region may be .195 inch, and the thickness of the wall portion overlying the intake valve region of the combustion chamber may be .23 inch. Therefore the wall portion '24 over the generally hotter section of the compressed charge,'due' to the heat from the exhaust valve (not shown) and surrounding parts, v has been made thinnner' than-the wall portion over the laterally adjacent intake valve region to promote the dissipation by the cooling means of the heat from this portion 24 of'the combustion of the chamber whereby to balancethe Wall temperatures of the combustion chamber for the reasons above set forth.

If it be assumed that Figu're 1 illustrates "a bustion chamber 2fl-2|22 and this charge is ignited by spark plug 25 then the flame propagation. will begin at the spark plug and progress through the compressed charge and strike the surface 26 of the combustion chamber with great severity because it is at approximately the point 28 that the burning charge is caused to suddenly change its course and be directed downwardly into the cylinder. I have discovered that this point 26 is probably the hottest section of the combustion chamber wall, and for that reason I have made the wall section at this point thinner than at any other section by providing a'depression, 21 in the head plate to bring the cooling water as close to the point 26 as practicably possible.

From the above it will be seen that the wall temperatures of my combustion chamber are, by the expedient described, heat balanced, so to speak, to prevent the residual heat in certain sections from. tooearly igniting said sections of the compressed charge and prevent other sections from cooling portions of the compressed charge before it is ignited.

I have pointed out above that in making cast iron cylinder heads, the molding technique may often require wall thicknesses in excess of those properly adapted to promote a balanced temperature for the walls 01' the finished combustion chamber. Accordingly, it becomes important to be able, when the combustion chamber walls cannotbe cast of the proper thickness originally, to cast them heavier than need be, and thereafter machine them to the desired thickness. This head in such a manner that one can machine the surfaces over which the cooling medium is to come in contact after the head plate has been cast. Broadly speaking, my invention comprises,

' in addition to the means for balancing the wall temperatures of the combustion chamber, means for constructing what may be described "as an assembled water jacket, as distinguished from one Referring now to Figure 7, wherein I show a modifiedform of water jacket, it will be seen that the head plate 5 is confined. between a'cover 40 a and a flat suitably perforated metal plate M. In this structure, an outwardly extending flange 42 is formed about. the cover 40 and welded in any suitable manner to the edge of the plate 4| after the head plate 5 is disposed therebetween. A gasket 43is employed in the usual way and for the usual purpose between the assembled head 1 v and cylinder block 44. It will be understood that .7

the perforations referred to in the plate 4| conform and register with those in. the gasket 43.

The modification shown 'in' Figure 7 also illusmite thatthe head 5 is coated at 45 with a spa-- cially selected insulating material comprising a I binder and a filler.. I prefer-.touse asphalt as a binder and graphite as a filler a'ndtthe purpose of.

approximately that of a paint coat. In cases I where it is desired to greatly retardor insulate the heat flow, a siliceous'material may beused, such as cement, fullers earth, or ground quartz. 'I'he function of the coating is to retain inthe cylinder head the proper amount of heat and be able to do properly prepared compressed charge in the com.- so without makingthe casting thicker than necessary for structural considerations. I have found,

therefore, that it is cheaper to make a thin casting, although one which is strong enough for structural purposes, but which would not of itself have the proper heat retention qualities, and supply those qualities to the casting by means of the coating.

Attention is also directed to the modified manner of sealing the water jacket to the spark plug bosses. In the form shown in Figure 1, wherein the edge i1 is expanded into a recess formed in the top of the spark plug boss, it has at times been found that certain materials may be cracked during the expansion operation. In Figure 7, however, the corresponding edge 48 of the cover 40 is clamped by the spark plug to the top of the boss and the water jacket sealed at this point, to a finished circumferential surface 49 formed on the boss, by being pressed over the top thereof. A depression 50 is formed in the water Jacket about the boss to prevent the normal expansion and contraction of the metal from breaking the sea] at this point. v

Attention is also directed to a further modification in the form of the water jacket shown in Figure '7 in that it is formed with an offset 5| to reduce the volume of water disposedover the normally cooler portion of the head which tends to elevate the temperature thereof. In other words, the reduced quantity of cooling water, available at the right-hand edge of the head plate shown in Figure '7 over the thick wall 23, tends to further decrease the dissipation of heat from this section of the combustion chamber.

While I have described what seems now-to be the preferred embodiments of my invention, it is conceivable that various modifications in the configuration, composition and disposition of the component elements which make up my invention as a whole, as well as in the selective combination and application of the respective elements, may

occur to those skilled in the art, and no limitation is intended by the phraseology of the foregoing description or illustrations in the accompanying drawings.

What is claimed is:

1. An internal combustion engine having a head with water cooled walls defining a combustion chamber in proximity to intake valve means which normally tends to maintain the adjacent wall at a relatively low temperature, and exhaust valve means which normally tends to maintain the adjacent wall at a relatively high temperature, the thickness of that portion of said wall in proximity to said intake valve means being relatively thick and the thickness of that portion of said wall in proximity to said exhaust valve means being relatively thin, whereby uniform combustion wall temperature during the power stroke of the engine is maintained.

2. An internal combustion engine having a head with water cooled walls defining a combustion chamber in proximity to intake valve means and a cylinder portion, both of which normally tend to maintain the adjacent wall at a relatively low temperature, and exhaust valve means which normally tends to maintain the adjacent wall at relatively high temperature, the thickness of that portion of said wall in proximity to said intake valve means and cylinder portion being relatively thick and the thickness of that portion ofsaid wall in proximity to said exhaust valve means beingrelatively thin, whereby uniform combustion wall temperature during the power stroke of the engine is maintained.

3. A head for ail internal combustion engine cylinder block, said head having a combustion chamber forming wall overlying the cylinder and the intake and exhaust valve ports for said cyl-.

inder in said block, said wall being divided into areas of differential heat transfer capacity, the area of great heat transfer capacity overlying the exhaust port region of the block and the areas of lesser heat transfer capacity overlying the intake port and cylinder region's oi the block, whereby niform combustion wall temperature during an angularly positioned relatively small region of greater heat transfer capacity joining the areas overlying the intake port and cylinder regions of the block, whereby uniform combustion wall temperature during the power stroke of the engine is maintained.

5. Ahead for an internal combustion engine cylinder block, said head having a combustion chamber forming wall overlying the cylinder and the intake and exhaust valve ports for said cylinder in said block, said wall being divided into areas of differential heat transfer capacity, the area of minimum heattransfer capacity overlying the cylinder region, the area of maximum heat transfer capacity overlying the exhaust port region and the area of intermediate heat transfer capacity overlying the intake port area of the block, whereby uniform combustion wall temperature during the power stroke of the engine is maintained.

' 6. A head for an internal combustion engine cylinder block, said head having a combustion chamber forming wall overlying the cylinder and intake and exhaust valve ports for said cylinder in said block, said wall being divided into areas of differential heat transfer capacity, the area of minimum heat transfer capacity overlying the cylinder region, the area of maximum heat transand the area of intermediate heat transfer capacity overlying the intake port area and extending a substantial distance over the center of the cylinder region, whereby combustion wall temperature during the powerstroke of the engine is maintained.

7. A head for an internal combustion engine cylinder block, said head having a combustion chamber forming wall overlying the cylinder and intake and exhaust valve ports for said cylinder in said block, said wall being divided into areas of heat transfer capacity, the area of minimum heat transfer capacity overlying the cylinder region, the area of great heat transfer capacity overlying the exhaust port region, and the area of intermediate heat transfer capacity overlying the intake port area and extending a substantial distance over the center of the cylinder region, and an angularly positioned relatively small region of maxlmumheat transfer capacity adjoining the areas overlying the intake port and cylinder refer capacity overlying the exhaust port region,

gions of the block, whereby uniform combustion 8. A head for-an internal combustion engine maximum heat transfer capacity overlying the exhaust port region of the block, and the areas of lesser heat transfer capacity overlying the intake port and cylinder regions of the. block, whereby uniform combustion wall temperature during the 5 power stroke of the engine is maintained.

ALFRED SCHWARZ. 

